Incorporation of pink pepper residue extract into chitosan film combined with a modified atmosphere packaging: Effects on the shelf life of salmon fillets.

Fresh salmon safety and quality is a major concern of consumers. In the current research, the effects of chitosan films incorporated with pink pepper residue extract and combined with modified atmosphere packaging (100% CO2) on quality properties of skinless salmon fillets during refrigerated storage (2 °C) were evaluated in the course of 28 days. Two different treatments as chitosan film (CF) and chitosan film incorporated with pink pepper residue extract (CFPP) and a control were compared. Salmon fillets were assessed for physicochemical (pH, WHC, TPA, Cie L*a*b*, TMA, TBA, value K), microbiological (mesophilic and psychrotrophic count, and lactic acid bacteria) and sensory properties. The results showed that CF and CFPP significantly reduced lipid oxidation relative to the control. Bacterial counts were significantly lower in CFPP, contributing to the significant reduction of trimethylamine. For sensory evaluation, CF and CFPP presented satisfactory results of off-odor and overall appearance. Despite being similar to the control, CFPP showed the lowest off-odor score. The results indicated that CFPP were more effective in maintaining the quality of salmon fillets during refrigerated storage.

Listeria monocytogenes incidence changes and diversity in some Brazilian dairy industries and retail products.

Listeria monocytogenes can cause listeriosis, a severe foodborne disease. In Brazil, despite very few reported cases of listeriosis, the pathogen has been repeatedly isolated from dairies. This has led the government to implement specific legislation to reduce the hazard. Here, we determined the incidence of L. monocytogenes in five dairies and retail products in the Southeast and Midwest regions of Brazil over eight months. Of 437 samples, three samples (0.7%) from retail and only one sample (0.2%) from the dairies were positive for L. monocytogenes. Thus, the contamination rate was significantly reduced as compared to previous studies. MultiLocus Sequence Typing (MLST) was used to determine if contamination was caused by new or persistent clones leading to the first MLST profile of L. monocytogenes from the Brazilian dairy industry. The processing environment isolate is of concern being a sequence-type (ST) 2, belonging to the lineage I responsible for the majority of listeriosis outbreaks. Also, ST3 and ST8 found in commercialized cheese have previously been reported in outbreaks. Despite the lower incidence, dairy products still pose a potential health risk and the occurrence of L. monocytogenes in dairies and retail products emphasize the need for continuous surveillance of this pathogen in the Brazilian dairy industry.

Biofilm-producing ability of Listeria monocytogenes isolates from Brazilian cheese processing plants.

The persistence of Listeria monocytogenes in food industry environments has been associated to the ability of specific isolates to produce biofilms. This study aimed to evaluate the biofilm production of 85 L. monocytogenes strains previously isolated from samples of cheese, brine and the environment of two cheese processing plants located in São Paulo, Brazil. The L. monocytogenes isolates belonged to serotypes 4b, 1/2b and 1/2c, yielded 30 different pulsotypes by pulsed-field gel electrophoresis (PFGE), and were submitted to biofilm-formation assays on polystyrene microplates and stainless steel coupons incubated statically at 35±0.5°C for 48h. All isolates from different sources showed ability to produce biofilms on polystyrene microplates, from which 21 (24.7%) also produced biofilms on stainless steel. Four isolates (4.7%) belonging to four different pulsotypes were classified as strong biofilms-producers on polystyrene microplates, while isolates belonging to four pulsotypes previously evaluated as persistent had weak or moderate ability to produce biofilms on polystyrene microplates. No relationship between the serotypes or pulsotypes and their biofilm-forming ability was observed. This study highlights the high variability in the biofilm production among L. monocytogenes strains collected from cheese and cheese-production environment, also indicating that strong biofilm-formation ability is not a key factor for persistence of specific isolates in cheese processing plants.

Effect of peracetic acid on biofilms formed by Listeria monocytogenes strains isolated from a Brazilian cheese processing plant

ABSTRACT This study aimed to investigate the effect of peracetic acid (PAA, 0.5%) on adherent cells of three strains of Listeria monocytogenes strains belonging to serotypes 4b and 1/2b that had been previously isolated from the environment of a Brazilian cheese plant. The assays were conducted using polystyrene microplates and stainless steel coupons and the adhered cells were treated with PAA for 60, 120 and 180 s. On stainless steel, biofilms were partially inactivated by PAA after 60 s and almost 100% of the cells were damaged within 180 s using epifluorescence microscopy with LIVE/DEAD® staining. On polystyrene microplates, PAA decreased (P<0.05) biofilm biomass produced by the three L. monocytogenes isolates at 60 s, when compared with controls (no PAA treatment). However, PAA did not completely eliminate L. monocytogenes cells on polystyrene microplates (decreasing 1.8-2.5 log cycles after treatment with PAA for 180 s). The correct concentration and contact time of PAA is critical for eliminating biofilms formed by L. monocytogenes on stainless steel surfaces, although further studies are needed for defining efficient PAA treatments to remove adherent cells of this pathogen on plastic polymers

Microbial deterioration of vacuum-packaged chilled beef cuts and techniques for microbiota detection and characterization: a review

Gas production from microbial deterioration in vacuum-packs of chilled meat leads to pack distension, which is commonly referred as blown pack. This phenomenon is attributed to some psychrophilic and psychrotrophic Clostridium species, as well as Enterobacteria. The ability of these microorganisms to grow at refrigeration temperatures makes the control by the meat industry a challenge. This type of deterioration has been reported in many countries including some plants in the Midwestern and Southeastern regions of Brazil. In addition to causing economic losses, spoilage negatively impacts the commercial product brand, thereby impairing the meat industry. In the case of strict anaerobes species they are difficult to grow and isolate using culture methods in conventional microbiology laboratories. Furthermore, conventional culture methods are sometimes not capable of distinguishing species or genera. DNA-based molecular methods are alternative strategies for detecting viable and non-cultivable microorganisms and strict anaerobic microorganisms that are difficult to cultivate. Here, we review the microorganisms and mechanisms involved in the deterioration of vacuum-packaged chilled meat and address the use of molecular methods for detecting specific strict anaerobic microorganisms and microbial communities in meat samples.

Microbial deterioration of vacuum-packaged chilled beef cuts and techniques for microbiota detection and characterization: a review.

Gas production from microbial deterioration in vacuum-packs of chilled meat leads to pack distension, which is commonly referred as blown pack. This phenomenon is attributed to some psychrophilic and psychrotrophic Clostridium species, as well as Enterobacteria. The ability of these microorganisms to grow at refrigeration temperatures makes the control by the meat industry a challenge. This type of deterioration has been reported in many countries including some plants in the Midwestern and Southeastern regions of Brazil. In addition to causing economic losses, spoilage negatively impacts the commercial product brand, thereby impairing the meat industry. In the case of strict anaerobes species they are difficult to grow and isolate using culture methods in conventional microbiology laboratories. Furthermore, conventional culture methods are sometimes not capable of distinguishing species or genera. DNA-based molecular methods are alternative strategies for detecting viable and non-cultivable microorganisms and strict anaerobic microorganisms that are difficult to cultivate. Here, we review the microorganisms and mechanisms involved in the deterioration of vacuum-packaged chilled meat and address the use of molecular methods for detecting specific strict anaerobic microorganisms and microbial communities in meat samples.

Avaliação de métodos para enumeração de microrganismos aeróbios mesófilos e coliformes em leite cru / Evaluation of methods for enumeration of microorganisms aerobic mesofilos and coliformes in raw milk

Os métodos rápidos de análise microbiológica de alimentos apresentavam vantagens sobre os métodos convencionais no que se refere à simplificação do trabalho no laboratório, redução de tempo na obtenção de resultados e diminuição de custos das análises. Nos últimos anos, foram desenvolvidas uma série de métodos rápidos para análises microbiológicas. Especificamente para a indústria de laticínios, a evolução desses métodos visa atender às necessidades, com respeito: à aquisição de leite cru, ao controle de processamento à avaliação do produto final, ao controle de armazenamento e distribuição dos produtos. Entre as diversas tecnologias alternativas estão os sistemas Petrifilm e o Sim-Plate. Neste estudo foram feitas avaliações das placas Petrifilm e Sim-Plate para contagem total de bactérias aeróbias mesófilas e coliformes, em comparação com os métodos convencionais de análise de leite cru. A análise de regressão simples dos dados mostrou forte correlação entre os métodos, tanto para a enumeração de bactérias aeróbias mesófilas (r³ 0,97) como para coliformes (r³ 0,95).

Avaliação das condições microbiológicas de carnes de animais silvestres no município de São Paulo / Evaluation of meat microbiology of wild animals

O interesse por espécies animais não convencionais, para a suplementação de proteína animal, é crescente, particularmente nos países africanos e asiáticos, porém, a utilização dessas fontes de alimento ainda é pouco documentada e quase não se sabe sobre as condições microbiológicas das carnes disponíveis para consumo. Avaliou as condições microbiológicas das carnes de capivara (Hydrochaeris hydrochaeris), cateto (Tayassu tajacu) e javali (Sus scrofa scrofa) in natura comercializadas no Brasil, município de São Paulo. Um total de vinte e sete amostras de carne de capivara, cateto e javali foram analisadas em laboratório e verificado o grau de contaminação por mesófilos aeróbios totais, psicrotróficos, Staphylococcus aureus, Clostridium sulfito-redutores, coliformes totais e fecais e Salmonella. 22 por cento das amostras de carne de cateto apresentaram-se impróprias para o consumo humano devido à presença de Salmonella. 11 por cento das amostras das carnes de capivara e javali e 22 por cento das amostras de cateto apresentaram contagens elevadas de S. aureus, maiores que o limite máximo estabelecido pela resolução RDC nº12 da Agência Nacional de Vigilância Sanitária (ANVISA) de 02 de janeiro de 2001, para produtos cárneos crus, resfriados ou congelados, uma vez que a resolução não cita tais padrões para carne in natura. A análise estatística descritiva apresentou um elevado coeficiente de variação entre as 9 amostras analisadas para cada tipo de carne. Esse alto grau de variação mostra que as condições microbiológicas das amostras não apresentaram uniformidade no decorrer das análises.